In applying chemicals to a field, the positioning of the tanks which hold the chemicals has varied from being supported at the rear of the tractor frame, to being carried separately on an implement, to being mounted at the sides of the tractor frame ahead of the rear wheels. Today, the most common position is the latter.
The position of these tanks in relation to the tractor can affect the manner in which the tractor can be used as well as its driving characteristics. One problem with placing the tanks at the sides, ahead of the rear wheels, is that visibility of the ground alongside and in front of the driver is restricted, making it difficult to accurately follow crop rows and to watch for small animals. A second problem associated with this placement of tanks is that the operator is hampered in mounting and dismounting the tractor. These problems are due not only to the location of the tanks themselves, but also to that of the mounting hardware and structure.
In addition, when these tanks are mounted forward of the rear axle, considerable weight is shifted towards the front axle. Since tractors are generally designed to operate most effectively when additional loads are centered over the rear axle, difficulties in handling, particularly in relation to the turning characteristics of the tractor, are experienced. More importantly, the resulting stress to the front axle and wheels could be hazardous.